title: Lineage diversification and recombination in type-4 human astroviruses.
abstract: Human astroviruses (HAstVs) are important enteric pathogens and can be classified genetically and antigenically into eight types. During surveillance of HAstVs in Italy, type-4 HAstVs were detected only sporadically and found to cluster into two distinct genetic groups. Upon sequence analysis of the 3' end of the polymerase gene (ORF1b) and of the full-length ORF2, the 2008 type-4 HAstV strains were characterised as a novel ORF2 genetic lineage, designated as 4c. The 2008 type-4 HAstVs also shared the ORF1b gene with similar HAstV-4c strains detected globally, thus displaying a conserved ORF1b/ORF2 asset. By interrogation of the databases, this novel lineage 4c accounted for 60.8% of the type-4 strains identified worldwide and the vast majority of recent type-4 HAstVs. The 2002 type-4 HAstVs displayed a type-4b ORF2, whereas in the ORF1b they resembled type-1 HAstVs. This inconsistency suggests a possible recombinant origin, with the RNA switch taking place upstream the ORF1b/ORF2 junction region. Also, recombination likely played a role in the diversification of the ORF2 of the three type-4 lineages. Multi-target analysis is required for appropriate characterisation and identification of recombinant HAstVs.
authors.affiliation: Dipartimento di Medicina Veterinaria, Università Aldo Moro di Bari, Valenzano, Italy.
authors.forename: Vito
authors.initials: V
authors.lastname: Martella
authors.forename: Maria C
authors.initials: MC
authors.lastname: Medici
authors.forename: Valentina
authors.initials: V
authors.lastname: Terio
authors.forename: Cristiana
authors.initials: C
authors.lastname: Catella
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Bozzo
authors.forename: Fabio
authors.initials: F
authors.lastname: Tummolo
authors.forename: Adriana
authors.initials: A
authors.lastname: Calderaro
authors.forename: Floriana
authors.initials: F
authors.lastname: Bonura
authors.forename: Marzia
authors.initials: M
authors.lastname: Di Franco
authors.forename: Krisztiàn
authors.initials: K
authors.lastname: Bányai
authors.forename: Giovanni M
authors.initials: GM
authors.lastname: Giammanco
authors.forename: Simona
authors.initials: S
authors.lastname: De Grazia
mesh_terms: D000595:Amino Acid Sequence; D019350:Astroviridae Infections / Q000821:virology*; D001483:Base Sequence; D036022:Capsid Proteins / Q000235:genetics*; D005243:Feces / Q000821:virology; D005759:Gastroenteritis / Q000821:virology*; D014644:Genetic Variation; D006801:Humans; D001257:Mamastrovirus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics*; D011995:Recombination, Genetic; D016415:Sequence Alignment; D017423:Sequence Analysis, RNA; D017386:Sequence Homology, Amino Acid
chemical_list: D036022:Capsid Proteins; D012367:RNA, Viral; D012324:RNA-Dependent RNA Polymerase
keywords: Astrovirus; Epidemiology; Genotyping; Italy; Viral gastroenteritis